The present invention relates to computer controlled conveyor systems, and more particularly to such systems capable of routing conveyor vehicles to selected destinations and preventing intervehicle collisions.
A wide variety of conveyor systems have been developed incorporating computers and/or communication systems for various purposes. One particularly useful system is that sold by the assignee of the present invention under the trademark CARTLING. This system includes an overhead conveyor track network and a plurality of self-propelled vehicles confined to the network for movement therealong. The track network is conceptually divided into segments, and a hardware logic module is associated with each segment. Circuit cards are provided, and each interconnects up to four hardware logic modules. If a vehicle is present on a segment and drawing current, the associated hardware logic module registers a "present signal" so that the circuit card knows that a vehicle is present on that segment. The circuit cards "block" one or more track segments behind the "vehicle present" segment to prevent intervehicle collisions. The vehicles are identified by an FM signal superimposed on the drive/block signal. Code readers at switches identify the vehicles and make switching decisions in response thereto. A central control computer is provided, and the various circuit cards and switching stations are hard-wired to each other and serially to the central computer to insure that vehicles are delivered to desired destinations.
Although constituting a significant advance, the CARTLING system is not without its drawbacks. Most significantly, the system is "wire intensive" requiring an extensive network of wires to interconnect the hardware logic modules, the circuit boards, the switching stations, and the central control computer. Such wiring is extremely complicated and therefore expensive. Further, such wiring is difficult to service and any modification to the system requires extensive rewiring.
Although computers have been integrated into other conveyor systems for various purposes, these computer systems do not provide the desired communication and/or control for present day manufacturing and warehousing environments.
It is often desirable to weigh conveyed articles in a conveyor system. Weighing is typically accomplished by providing a weigh station and routing the articles to be weighed through the station. This arrangement has several drawbacks. First, articles to be weighed must be shuttled through the station, often requiring additional conveying time. Second, the weight of the article is determined only at the time of its presence at the weigh station. Weights at other times must be assumed.